Stoker control



Nov. 20, 1934. c. KAY

STOKER CONTROL Filed Oct. 10, 1931 N m M U 5 m v.Jrvoank-m CH4 V/M KAPatented Nov. 20, 1934 UZ-E E E STATES PATENT orr cs Claims.

This invention relates to a stoker control, and more particularly adevice for shutting off motive power or giving alarm when certainabnormal conditions exist in the feed hopper of a 5 Stoker conveyor.

The principal object of the invention is to prevent the objectionablecondition which results frequently in ordinary stokers when smoke andfumes backpass from the firebowl of the stoker into the feed hopper, andfrom there into the building where the apparatus may be situated.

Another object is, that the device shall be simple, inexpensive, and notliable to get out of order when in the hands of unskilled users.

In furnace stokers, fine fuel, such as slack coal, is conducted from afeed hopper to the fire, by means of a suitable conveying element, suchas a rotatable screw.

Coal usually contains a certain amount of moisture, which causes it topack in the feed hopper, and even though agitatorsare used, an archingof the fuel is liable to occur in the feed hopper above the screwconveyor. The result is that the fuel in the lower part of the hoppermay be entirely exhausted, while from the outside,

the hopper may look as though it contains a sumcient quantity.

When such a condition as the above exists, the open passage through theconveyor and the lower part of the hopper allows smoke and fumes fromthe furnace to backpass into the building, which is highly annoying andeven dangerous.

In my improved device, I provide one or more pivoted arms in proximityto the agitator of a Stoker, the arm or arms being so located that,

as the fuel becomes exhausted in the neighborhood of the agitator,gravity as the actuating force, will cause the arms to drop, therebyoperating an electric switch and shutting off the motive power whichdrives the conveyor. If desired, an alarm may be sounded to give noticeto the attendant that the fuel must be replenished.

The features of this invention for which the a protection of LettersPatent of the United States is desired, are collectively grouped in theclaims concluding this specification.

In the drawing, which illustrates one embodiment of this invention,

Fig. 1 represents a plan of a stoker feed hopper with my device appliedthereto, some parts in the background being omitted;

Fig. 2, a side elevation, portions being broken away to show certainparts in section;

Fig. 3, an end elevation looking from the stoker side, portions beingbroken away to show parts inside the hopper; and g V I Fig. 4, adiagram, in perspective, showing the parts constituting my improvement,separately from the hopper.

Referring to the drawing, the numeral 10 indicates the feed hopper of anordinary stoker, to the lower portion of which is attached .a conveyorcasing 12 as usual. Within this casing is the usual conveyor worm orscrew 14, which also extends through the lower portion of the hopper, asindicated in Fig. 2.

Immediately above the conveyor worm is the usual agitating wheel 15,thisbeing rigidly mounted on a shaft 16 which in turn, is rotatablymounted in bearings 17. The agitating wheel carries a bail or sweep 18,preferably as an integral part thereof, while the sweep may carry one ormore horns 19. The conveyor'worm and the agitating wheel are arranged toturn in unison, and are driven from an outside source of power (notshown) in any. usual manner.

What has so far been described, forms no part of my invention, exceptingwhen used in combination with those parts which will now be re- 30ferred to. i

Oscillatingly mounted backof the agitating wheel 15, are one or morearms 20. Preferably two arms are used, which straddle the agitatingwheel, and these armsare so positioned as to be 5 lifted by the sweep ofthe agitating wheel. The arms may be mounted in any suitable manner soas to rock pivotally, for example, the arms may be rigidly mounted on a,shaft 21, and the latter may be rotatably mounted in the hopper onwalls, as indicated at 24. One end of shaft 21 may be extended outsidethe hopper and carry an arm 25, to which is pivoted a rod 26, and thisin turn may be pivoted to the blade 27 of a knife switch 28. This switchhas prongs 29 and 30,'between which the blade 27 is operatively mounted.The prongs 29 and 30 form switch terminals, and may be connected inseries with an electric motor (not shown) by means of conductors 31 and32. The switch terminals may be mounted on a base 34, preferably made ofinsulating material.

In using the device, the arms 20 are first lifted into a raisedposition, by hand or otherwise, the raised position being indicated inFigs. 2, 3 and 4. This is done before filling the hopper with fuel, andnaturally, as the filling proceeds, fuel is deposited underneath arms 20and serves to hold these in the. elevated position.

In the elevated position of arms 20, knife switch 28 is closed. Now, aslong as substantially the desired minimum quantity of fuel remainsunderneath arms 20, these will not be allowed to drop into a positionvery much lower than that shown in Fig. 2. When, however, the fuelsupply becomes further exhausted, arms 20, after being contacted bysweep 18 during a part of each revolution of the latter, finally fall toa point where there will no longer be sufficient fuel beneath them,

when released from sweep 18 inthe course of its revolution, to holdblade 27 in engagement with terminal members 30. As soon as blade 2'7 isreleased from terminal members 30, the motor will be stopped, and nomore fuel will be taken away by the conveyor until proper runningconditions have again been established.

Thus, the fuel in the hopper will never become exhausted below a certainpredetermined level,

' such as indicated by the position 20--1 of arms 20, where they rest onhub l5l of wheel 15. This insures always a sufficient supply of fuelto'act as a plug in the lower part of the hopper, and prevents at alltimes, the backpassing of smoke or fumes from the furnace (not shown)through the conveyor casing 12.

Obviously, the weight of arms 20 must be sufficient to cause theoperation of the device by gravity.

It is to be noted that the device is operative to indicate the loweringof the normal fuel level to substantially a predetermined limit, but itsespecial sphere of usefulness is to prevent the exhaustion of fuel.below this limit when the fuel in the upper part of the hopper outsidethe range of the agitating wheel, is arched over so as to mislead anattendant as to the true conditions inside the hopper.

The upward limit of travel of arms 20 may extend to any suitable point,such, for instance,

as indicated by the dotted lines 202, in Fig. 2.

A sufiicient distance is allowed in prongs 30, to give blade 27' thenecessary movement corresponding to the travel of arms20.

The length of these arms is such that they shall lie within the clearingzone of the agitator, which zone in this instance may be determinedsubstantially by the outermost portions, radially, of the agitatingwheel 15 and its sweep 18, which latter preferably extends transverse tothe plane of rotation of the agitating wheel,

If it should be desired to give an alarm, instead of stopping the motor,switch 28 could be connected in circuit with an electric bell or otheralarm. On the other hand, both the stopping of the motor and thesounding of an alarm might be provided for if preferred.

7 The joints between connecting rod 26 and members 25 and 27, shouldallow the necessary latitude to prevent binding between the respectiveparts. ca

While a specific embodiment of this invention is herein shown anddescribed, it is to be understood that various changes could be madetherein without departing from the spirit and scope of the invention asdefined in the claims.

Having fully described my invention, what I claim is:

l. The combination with a stoker having a hopper, a conveyor leading outof said hopper and an agitator revoluble in said hopper above theconveyor, of a control mechanism including an arm disposed to be raisedand lowered within the circle described by said agitator, and meansactuated by the movement of said arm for the purpose of controlling themotive power of said conveyor.

2. The combination with a stoker having a hopper, a conveyor leading outof said hopper and a revoluble wheel having agitating members describinga cylindrical space above said conveyor, 01' a control mechanismincluding an arm movable in the said cylindrical space and engageable bythe said agitating members, means for imparting motion to said conveyor,and means whereby travel of said movable armis effective to start orstop, as the case may be,

said conveyor.

3. The: combination with a stoker or the like, having a hopper, aconveyor leading out of said hopper, an agitating wheel having arevoluble sweep above said conveyor, and a motor for driving saidconveyor, of a control mechanism including an arm pivoted alongside saidagitating wheel, said arm being engageable by the revoluble sweep, andhaving motion within the circular zone defined by revolution of saidsweep, and an electric switch connected to said pivoted arm, said switchbeing operative to start and stop said motor.

4. The combination with a stoker or the like, 115 having .a hopper, aconveyor leading out of said hopper, and an agitating wheel having arevoluble sweep above said conveyor, of a control mechanismincluding amovable arm disposed for engagement by said sweep, and an electricswitch 124] actuated by said movable arm, said switch being closed whenthe movable arm is raised to certain points, and opened when the movablearm is lowered to certain other points.

5. The combination with a stoker comprising 125 a container for fuel, aconveyor leading out of said container, and an agitator for looseningfuel above said conveyor, said agitator having a sweep extendingtransverse to the plane of rotation of the'agitator; of a movable armengage- 130 able by said sweep and an electric switch operativelyconnected to said movable arm.

CALVIN KAY.

